Coast redwoods grow taller, but giant sequoias are the biggest trees on Earth by sheer volume. A full-grown sequoia is basically a living skyscraper made of wood - over 90 metres tall, with a trunk wider than a small swimming pool. They only grow naturally on a few slopes of California’s Sierra Nevada.
Their secret weapon is bark. It can be nearly a metre thick, soft and spongy, and packed with chemicals that resist fire and insects. Forest fires sweep through sequoia groves all the time and the old giants just shrug them off, while younger trees and brush get cleared away.
Sequoias actually need those fires. Their cones are sealed shut with sticky resin and only pop open in heat. Without flames, the seeds stay locked up. So the world’s biggest trees depend on the planet’s most destructive force just to make babies.
